A hydraulic brake system for a vehicle which has expanded functionality, where a pre-charge occurs in the brake system upon deactivation of the cruise control, reducing the time needed to generate pressure in each brake unit, reducing stopping distance. The pre-charge function involves generating pressure in each caliper of the brake system upon deactivation of the cruise control function of the vehicle, such that the hydraulic brake system is pre-charged prior to the driver of the vehicle applying force to the brake pedal, which reduces stopping distance. One aspect of the pre-charge function includes generating enough pressure such that the brake pads contact each corresponding rotor. Another aspect of the pre-charge function includes generating enough pressure such that the brake pads apply force to each corresponding rotor, providing a minimum amount of deceleration prior to the driver of the vehicle applying force to the brake pedal.
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1. An apparatus, comprising:
a braking system for a vehicle, including:
a hydraulic electronic control unit;
at least one brake unit operable for being controlled by the hydraulic electronic control unit;
a cruise control function operable for configuring the vehicle to maintain a constant speed;
at least one rotor;
a plurality of brake pads, a first of the plurality of brake pads located on a first side of the at least one rotor, and a second of the plurality of brake pads located on a second side of the at least one rotor, the brake unit operable for configuring the plurality of brake pads to selectively apply force to the at least one rotor; and
a first air gap located between the first side of the at least one rotor and the first of the plurality of brake pads;
a pre-charge function which includes generating pressure in the at least one brake unit;
wherein the pre-charge function is activated by the hydraulic electronic control unit when the cruise control function is deactivated;
wherein the pre-charge function includes generating pressure in the at least one brake unit such that the first of the plurality of brake pads is in contact with the first side of the at least one rotor, and the second of the plurality of brake pads is in contact with the second side of the at least one rotor; and
wherein upon deactivation of the cruise control function and activation of the pre-charge function, as the pressure is generated in the at least one brake-unit, the first of the plurality of brake pads is moved towards the first side of the at least one rotor such that the first air gap is eliminated.
8. A braking system for a vehicle, comprising:
a hydraulic electronic control unit;
at least one brake unit operable for being controlled by the hydraulic electronic control unit;
at least one rotor;
a plurality of brake pads being part of the at least one brake unit, a first of the plurality of brake pads located on a first side of the at least one rotor, and a second of the plurality of brake pads located on a second side of the at least one rotor, the brake unit operable for configuring the plurality of brake pads to selectively apply force to the at least one rotor;
a cruise control function operable for configuring the vehicle to maintain a constant speed;
a pre-charge function which includes generating pressure in the at least one brake unit such that the first of the plurality of brake pads is in contact with the first side of the at least one rotor, and the second of the plurality of brake pads is in contact with the second side of the at least one rotor;
wherein the pre-charge function is activated by the hydraulic electronic control unit when the cruise control function is deactivated;
a first air dap located between the first side of the at least one rotor and the first of the plurality of brake pads;
a second air gap located between the second side of the at least one rotor and the second of the plurality of brake pads; and
wherein upon deactivation of the cruise control function and activation of the pre-charge function, as the pressure is generated in the at least one brake-unit, the first of the plurality of brake pads is moved towards the first side of the at least one rotor such that the first air gap is eliminated, and the second of the plurality of brake pads is moved towards the second side of the at least one rotor such that the second air gap is eliminated.
14. A method for reducing the stopping distance of the vehicle, comprising the steps of:
providing braking system for a vehicle;
providing a hydraulic electronic control unit being part of the braking system of the vehicle;
providing at least one brake unit being part of the braking system, the at least one brake unit operable for being controlled by the hydraulic electronic control unit;
providing at least one rotor being part of the braking system;
providing a plurality of brake pads being part of the at least one brake unit, a first of the plurality of brake pads located on a first side of the at least one rotor, and a second of the plurality of brake pads located on a second side of the at least one rotor, the brake unit operable for configuring the plurality of brake pads to selectively apply force to the at least one rotor;
providing a cruise control function operable for configuring the vehicle to maintain a constant speed; and
providing a pre-charge function being part of the braking system, the pre-charge function being activated by the hydraulic electronic control unit;
activating the pre-charge function after the cruise control function is deactivated, the pre-charge function generating pressure in the at least one brake unit such that the first of the plurality of brake pads is placed in contact with the first side of the at least one rotor, and the second of the plurality of brake pads is placed in contact with the second side of the at least one rotor;
providing a first air gap located between the first side of the at least one rotor and the first of the plurality of brake pads;
providing a second air gap located between the second side of the at least one rotor and the second of the plurality of brake pads;
deactivating the cruise control function;
eliminating the first air gap by moving the first of the plurality of brake pads towards the first side of the at least one rotor upon deactivation of the cruise control function and activation of the pre-charge function; and
eliminating the second air gap by moving the second of the plurality of brake pads towards the second side of the at least one rotor upon deactivation of the cruise control function and activation of the pre-charge function.
2. The apparatus of
a second air gap located between the second side of the at least one rotor and the second of the plurality of brake pads;
wherein upon deactivation of the cruise control function and activation of the pre-charge function, as the pressure is generated in the at least one brake-unit, the second of the plurality of brake pads is moved towards the second side of the at least one rotor such that the second air gap is eliminated.
3. The apparatus of
4. The apparatus of
a brake pedal in communication with the hydraulic electronic control unit, the hydraulic electronic control unit operable for controlling the pressure generated by the brake unit based on the amount of force applied to the brake pedal;
wherein the pre-charge function is activated prior to the driver of the vehicle applying force to the brake pedal.
5. The apparatus of
6. The apparatus of
7. The apparatus of
9. The braking system for a vehicle of
a brake pedal in communication with the hydraulic electronic control unit, the hydraulic electronic control unit operable for controlling the pressure generated by the brake unit based on the amount of force applied to the brake pedal;
wherein the pre-charge function is activated prior to the driver of the vehicle applying force to the brake pedal.
10. The braking system for a vehicle of
11. The braking system for a vehicle of
12. The braking system for a vehicle of
13. The braking system for a vehicle of
15. The method of
providing a brake pedal in communication with the hydraulic electronic control unit;
controlling the pressure generated by the brake unit based on the amount of force applied to the brake pedal using the hydraulic electronic control unit;
activating the pre-charge function prior to the driver of the vehicle applying force to the brake pedal.
16. The method of
17. The method of
18. The method of
providing the at least one brake unit as a plurality of brake units;
generating pressure in each of the plurality of brake units when the cruise control function is deactivated.
19. The method of
generating enough pressure in the at least one brake unit such that the first of the plurality of brake pads applies force the first side of the at least one rotor;
generating enough pressure in the at least one brake unit such that the second of the plurality of brake pads applies force to the second side of the at least one rotor;
decreasing the rotational speed of the at least one rotor as the first of the plurality of brake pads applies force the first side of the at least one rotor, and the second of the plurality of brake pads applies force to the second side of the at least one rotor.
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This application claims the benefit of Provisional Application 62/778,682, filed Dec. 12, 2018. The disclosure of the above application is incorporated herein by reference.
The invention relates generally to a braking system having a pre-charge function, where the pre-charge function is activated upon deactivation of a vehicle's cruise control function.
Hydraulic braking systems for vehicles typically include multiple braking units, each of which includes some type of actuator in electrical communication with a hydraulic electronic control unit (HECU). The actuator works with a caliper having a piston, and at least two brake pads to apply braking force to a brake rotor, or brake drum. The actuator is used to build pressure in one or more of the braking units, more specifically the caliper, and during operation of a vehicle having a hydraulic braking system, the pressure build-up is controlled by the HECU. This build-up of pressure typically occurs when the driver applies force to the brake pedal. When force is no longer applied to the brake pedal, fluid pressure in the calipers is relieved, and allowing the pistons to retract, releasing the brakes.
When the braking system is not in use, there is typically a gap between the rotor and each of the pads. Most hydraulic brake systems require a build-up of pressure in the braking units, such that each brake pad is positioned to be in contact with the corresponding rotor (eliminating the gaps) before any vehicle deceleration is achieved. This build-up of pressure, or “pre-charge,” typically occurs after application of force to the brake pedal by the driver. This pre-charge increases the amount of time needed to generate braking force to decelerate the vehicle, causing a delay in the generation of braking force, and therefore increases the stopping distance of the vehicle.
There are instances where deceleration of the vehicle may occur without the driver applying force to the brake pedal. One of the instances where this type of deceleration may occur is after the deactivation of the cruise control function. The driver of the vehicle may then apply force to the brake pedal to decelerate the vehicle, however, there is still no braking force generated by the braking units until after the pre-charge has occurred, which causes an increase in stopping distance of the vehicle.
Accordingly, there exists a need for a hydraulic braking system which has expanded functionality, such that the pre-charge occurs after the deactivation of the cruise control, and prior to the driver applying force to the brake pedal, which results in braking force being achieved upon the application of force to the brake pedal by the driver, decreasing stopping distance.
The present invention is a hydraulic brake system for a vehicle which has expanded functionality, where a pre-charge occurs in the brake system upon deactivation of the cruise control, reducing the time needed to generate pressure in each brake unit, and therefore reducing stopping distance. In one embodiment, the hydraulic brake system includes several brake units, and each brake unit includes a caliper, and one or more brake pads which selectively apply force to a brake rotor. Each caliper is in fluid communication with some type of actuator capable of generating hydraulic pressure. The hydraulic brake system includes a pre-charge function, where the pre-charge function involves generating pressure in each caliper upon deactivation of the cruise control function of the vehicle, such that the hydraulic brake system is pre-charged prior to the driver of the vehicle applying force to the brake pedal, which reduces stopping distance.
In one embodiment, the pre-charge function includes generating enough pressure in each caliper such that the brake pads contact each corresponding rotor. In another embodiment, the pre-charge function includes generating enough pressure in each caliper such that the brake pads apply force to each rotor, providing a minimum amount of deceleration prior to the driver of the vehicle applying force to the brake pedal.
In an embodiment, the present invention is a braking system for a vehicle, which includes a hydraulic electronic control unit, at least one brake unit operable for being controlled by the hydraulic electronic control unit, at least one rotor, and a plurality of brake pads being part of the brake unit. A first of the plurality of brake pads is located on a first side of the rotor, and a second of the plurality of brake pads located on a second side of the rotor. The brake unit is operable for configuring the plurality of brake pads to selectively apply force to the rotor.
The vehicle includes a cruise control function operable for configuring the vehicle to maintain a constant speed. The braking system also includes a pre-charge function which includes generating pressure in the brake unit such that the first of the plurality of brake pads is in contact with the first side of the rotor, and the second of the plurality of brake pads is in contact with the second side of the rotor.
In an embodiment, the pre-charge function is activated when the cruise control function is deactivated.
A first air gap is located between the first side of the rotor and the first of the plurality of brake pads, and a second air gap located between the second side of the rotor and the second of the plurality of brake pads. Upon deactivation of the cruise control function and activation of the pre-charge function, as the pressure is generated in the brake-unit, the first of the plurality of brake pads is moved towards the first side of the rotor such that the first air gap is eliminated, and the second of the plurality of brake pads is moved towards the second side of the rotor such that the second air gap is eliminated.
The braking system also includes a brake pedal in communication with the hydraulic electronic control unit. The brake pedal may be in electrical communication or in hydraulic communication with the hydraulic electronic control unit. The hydraulic electronic control unit is operable for controlling the pressure generated by the brake unit based on the amount of force applied to the brake pedal. In an embodiment, the pre-charge function is activated prior to the driver of the vehicle applying force to the brake pedal.
In one embodiment, the pre-charge function is activated when the vehicle is travelling on an exit ramp of a highway. In another embodiment, the pre-charge function is activated when the vehicle is travelling on the highway, and the driver of the vehicle anticipates having to decelerate the vehicle which may be due to an accident seen by the driver, or increased traffic volume.
In one embodiment, the braking system includes a plurality of brake units, wherein the pre-charge function includes generating pressure in each of the plurality of brake units when the cruise control function is deactivated.
In one embodiment, the pre-charge function includes generating enough pressure in the brake unit such that the first of the plurality of brake pads applies force the first side of the rotor, and the second of the plurality of brake pads applies force to the second side of the rotor, decreasing the rotational speed of the rotor.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:
The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.
A diagram showing a hydraulic braking system having a pre-charge function according to the present invention is shown in
The hydraulic braking system 10 also includes an electronic parking brake function. Each rear brake unit 14a,14b includes an electronic parking brake actuator 20a,20b, and each electronic parking brake actuator 20a,20b is used with a piston located in a corresponding caliper 22a,22b to generate braking force. By way of example, the first brake unit 14a, shown in
Referring again to
The brake system 10 also includes a tandem master cylinder (TMC), shown generally at 26. The TMC 26 is divided into various cavities, and has two pistons, one of which is connected to a connecting rod 28, and the connecting rod 28 is connected to and actuated by a brake pedal 30. There is a first primary feed conduit 32a connected to and in fluid communication with the rear brake system 16A and the TMC 26, and a second primary feed conduit 32b connected to and in fluid communication with the front brake system 16B and the TMC 26.
More specifically, the first primary feed conduit 32a is connected to and in fluid communication with a first accumulator 34a. There are also several other accumulators 34b,34c, and a low-pressure accumulator 36. The first primary feed conduit 32a splits, and is in fluid communication with a first solenoid valve 38a and a second solenoid valve 38b. There are also several other solenoid valves 38c,38d,38e,38f which are part of the rear brake system 16A. The second valve 38b includes a check valve 40a to provide for pressure relief. There are also several other check valves 40b,40c,40d,40e,40f, which are part of the rear brake system 16A and function to provide pressure relief when necessary. The rear brake system 16A also includes a pump 42 for generating or relieving fluid pressure in the rear brake system 16A, and a restriction point 44 for controlling pressure, and several other conduits (not labeled) which provide fluid communication between the various components of the rear brake system 16A, as shown in
The accumulators 34a,34b,34c,36, the solenoid valves 38a,38b,38c,38d,38e,38f, as well as the check valves 40a,40b,40c,40d,40e,40f, and the pump 42 all control the flow of fluid and the fluid pressure in the conduits and the pressure in each caliper 22a,22b,22c,22d. Both the rear brake system 16A and the front brake system 16B have some type of actuator, which in this embodiment is the TMC 26, which generates fluid pressure in the rear brake system 16a based on the amount of force that is applied to the brake pedal 30 to generate braking force to decelerate the vehicle. Referring again to
In operation, the driver of the vehicle applies force to the brake pedal 30, which generates pressure in the TMC 26, and therefore generates pressure in the brake systems 16A,16B. There is a pressure sensor 46 which detects this pressure increase, and information regarding the increase in pressure is transferred from the pressure sensor 46 to the HECU 12. More specifically, in the rear brake system 16a, based on the amount of force applied to the brake pedal 30, the TMC 26 is able to increase the pressure in the first caliper 22a, moving the piston 50 such that the pads 48a,48b apply force to the first rotor 18a, limiting or preventing rotation of the first rotor 18a. The other brake units 14b,14c,14d operate in a similar manner.
Referring now to
However, when there is no force applied to the brake pedal 30, and the rotor 18a is released and allowed to rotate freely, there are air gaps 52a,52b on each side of the rotor 18a, shown in
There are often instances when the driver of the vehicle is operating the vehicle in a cruise-control mode, where the cruise control function is activated, and the vehicle maintains a desired speed set by the driver. However, there are instances where the driver of the vehicle deactivates the cruise control, prior to applying force to the brake pedal 30, which (if the driver does not apply force to the accelerator pedal) results in the vehicle coasting. This may occur when the driver of the vehicle has moved to an exit ramp off a highway. Another instance where this may occur may be when driving on the highway, and the driver of the vehicle anticipates having to decelerate the vehicle, which may be due to an accident seen by the driver, or increased traffic volume.
The pre-charge function of the present invention functions to generate pressure in the caliper 22a, moving the piston 50 such that each pad 48a,48b moves towards the rotor 18a, and contacts the rotor 18a, eliminating both gaps 52a,52b, as shown in
Referring now to
Between time t0 and t1, the cruise control operating state 102 is active, the vehicle velocity 106a,106b is constant, there is no brake actuation 100, and the brake pressure 104a,104b is zero.
At time t1, the cruise control operating state 102 is changed from being active to being deactivated by the driver (i.e., the driver deactivates the cruise control function), and the vehicle velocity 106a,106b begins to decrease as a result of the vehicle coasting. Also, between time t1 and time t2, once the cruise control operating state 102 is changed to being deactivated, the pre-charge function of the present invention is activated, and the brake pressure 104a increases, such that the pressure in the caliper 22a moves each set of brake pads 48a,48b, eliminating the air gap 52a,52b on each side of the rotor 18a (as shown in
At time t2, the driver then applies force to the brake pedal, shown by the increase in brake actuation 100 at time t2, which also causes a further increase in brake pressure 104a beginning at time t2, such that force is applied to the rotor 18a by the pads 48a,48b, causing a decrease in the vehicle velocity 106a. If the brake actuation 100 is maintained, as shown in
When the pre-charge function is not used, the brake pressure between time t1 and time t2 is still zero. When the driver applies force to the brake pedal at time t2, the brake pressure 104b increases, but the initial increase in brake pressure 104b moves the brake pads 48a,48b to eliminate each air gap 52a,52b, such that no force is applied to the rotor 18a by the pads 48a,48b. Therefore, between time t1 and t2, and between time t2 and t3, there is no force applied to the rotor 18a by the pads 48a,48b, and the only decrease in the vehicle velocity 106b is the result of drag during the coasting of the vehicle. Once the pads 48a,48b have moved such that each air gap 52a,52b has been eliminated, force is then applied to the rotor 18a by the pads 48a,48b, which occurs at time t3. At time t3, the vehicle velocity 106b then begins to decrease as a result of force being applied to the rotor 18a by the pads 48a,48b. If the brake actuation 100 is maintained, as shown in
It is seen when looking at
The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
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